The invention relates generally to devices for maintaining a hitch pin securely in place so that it does not become inadvertently disengaged from the connection.
Hitch pins that connect the tongue of a towed vehicle, such as a farm implement, to the drawbar of a tractor or other prime mover are well known and have been used for many, many years. The hitch pin is generally inserted through aligned openings in the drawbar and tongue, and the common hitch pin has a collar near its upper end that prevents it from falling through the aligned openings but which allows limited vertical movement. It is also common practice to insert a retaining pin or clip through an opening near the lower end of the pin. However, these retaining pins or clips can become easily dislodged as the implement is drawn through agricultural fields. The retaining pin or clip thus becomes lost, and if it is not replaced, the pin can become disengaged from the drawbar and tongue creating a safety hazard.
To overcome the problem, numerous modifications have been made to the standard, simple hitch pin in an effort to resolve the problem. None of these to date have been satisfactory because of cost, complexity, difficulty to use, etc.
Another approach to maintaining the hitch pin in place is to provide a device that will block the head of the pin thereby preventing it from being pulled upwardly out of the hitch connection. A number of these locking devices are known, and they generally utilize a moveable component that is moveable to one of two positions, a blocking position or an unblocking position. However, when the device of this type encounters a force during use, it frequently will move to the unblocking position and will stay in that position until corrected. Other devices of this type will remain in a locked position but are very complex and difficult to use. Devices of the blocking type are shown, for example, in U.S. Pat. Nos. 2,593,247, 2,697,618, 3,061,334, 3,190,677, 3,522,958, 3,679,243, 3,685,864, 3,794,357, 4,394,031, 4,552,377 and 4,579,364. Some of these patents show devices of the blocking type that are utilized as safety devices for a trailer hitch in which the arm extends over a ball and socket hitch to keep the two together.
There is therefore a need for an improved means of assuring that a hitch pin will stay in place under practically all conditions. Such a device must be relatively simple, easy to use, not excessively expensive and almost foolproof. The present invention is directed toward a device which achieves all of these goals.